Polymeric rubber coating composition



Patented Aug. 3, 1943 POLYMERIC RUBBER COATING COMPOSITION Robert C. Swain, Riverside. and Pierrepont Adams, Stamford, Conn, assignors to American Cyanamid Company; New

corporation oi Maine No Drawing.

York, N. Y., a

Application October 26, 1940, Serial No. 363,004

4 Claims. (01. 260-3) f This invention relates to coating compositions containing polymerized rubber and melamineformaldehyde resins.

An object of this invention is to improv the physical and chemical properties of polymerized rubber compositions, e. g., sensitivity to solvents; reduction in thermoplasticity, hardness, heat resistance, etc.

Another object of this invention is to provide improved melamine-formaldehyde coating com positions. r

Still another object of this invention is to provide compositions containing polymerized rubber and compatible proportions of compatible melamine-formaldehyde resins.

These and-other objects are attained by blending polymerized rubber, otherwise known as cyclized rubber obtained by reacting the rubber with amphoteric metal halides, with a melamineformaldehyde resin which has been alkylated with an acyclic alcohol containing from 3 to 8 carbon atoms, wherein the molal ratio of formaldehyde to melamine is at least about 4:1 and wherein the proportion of melamine resin is less than about 40% (total solids weight basis). 7

The following examples in which the proportions are in parts by weight are given by way of illustration and not in limitation. The polymerized rubber used in the 'following examples is a product sold under the trade name Pliolite" by the Goodyear Tire and Rubber Company. The term polymerized rubber as used in the following examples is intended to cover only cyclized I rubber obtained by reacting the rubber with A composition containing these ingredients is.

' are applied to metal objects and baked at a tem-.

perature of about 135 C. for about one-half hour. The product is a hard, transparent coating having good film strength.

Example 2 Parts Melamine-formaldehyde Resin 13"-. I

Polymerized rubber (Pliolite) 75 A composition containing these ingredients is prepared by admixing'50 parts ,of melamineformaldehyde Resin B" solution (50% resin) with 300 parts of Polymerized Rubber Stock amphoteric metal halides.

Example 1 Parts. Melamine-formaldehyde Resin A 10 Polymerized rubber (Bliolite) 90 Solution. Films of the composition are applied to metal objects and baked at a temperature of about 135 C. for about one-half hour. 1 A clear, tough film is formed.

Example 3 Parts Melamine-formaldehyde Resin C 10 Polymerized rubber (Pliolite) A composition containing these ingredients is prepared by admixing 20 parts of melamineformaldehyde Resin C solution (50% resin) with 360 parts of Polymerized Rubber Stock Solution. Films of the composition are applied to metal objects and baked at a temperature of about C. for about one-half hour. The product formed is a very hard, clear coating.

' Example 4 p Parts Melamine-formaldehyde Resin D 25 Polymerized rubber ("Pliolite) '75 A composition containing these ingredients is prepared by admixing 50 parts of melamineformaldehyde Resin D solution (50% resin) with 300 parts of Polymerized Rubber Stock Solution. Films of the composition are applied tometal objects and baked at a temperature of about 135 C. for about one-half hour. A waterwhite film having good chemical properties is formed.

Example 5 Parts Melamine-formaldehyde Resin E 10 Polymerized rubber ("Plio1ite) 90 Example 6 Parts Melamine-formaldehyde Resin F 25 Polymerized rubber ("Pliolite) '75 A composition containing these ingredients is prepared by admixing 50 parts of melamineformaldehyde Resin F solution (50% resin with 300 parts of "Polymerized Rubber Stock Solution. Films of the composition are applied to metal objects and baked at a temperature of 1 about 135 C. for about one-half hour, to give a smooth, transparent flnish.

Example 7 Parts Melamine-formaldehyde Resin F 40 Polymerized rubber. ("Pliolite) 60 A composition containing these ingredients is v prepared by admixing 80 parts of melamine- Preparation of melamine-formaldehyde Resin A Y Parts Melamine (1 mol) 126 Formalin (4 mols) (37% formaldehyde in water) 324.4 n-Butanol t This mixture is placed in a reflux apparatus which is provided with a condenser and a suitable water trap throughwhich the reflux-condensate passes on its" return to the reaction chamber and in which the essentially aqueous fraction of the condensate may be separated from theessentially non-aqueous fraction and means is provided so that the former fraction may be drawn OK if desirable. The reaction mixture is refluxed at a temperatureof about 91-93 C. at atmospheric pressure for 6-12 hours. The water is removed by azeotropic distillation from the reaction mixture during the reflux operation beginning preferably after about 2-5 hours have elapsed and the water soremoved is separatedfrom the reflux condensate in the water trap. tillation about 550 additional parts of butanol are added gradually. when the reflux condensate is substantially anhydrous the vapor temperature aaaaoao tillation about 550 additional parts of butanol are added gradually. when the'reflux condensate is substantially anhydrous the vapor temperature will be about loo-105 C. The pressure is lowered sufllciently to reduce the vapor temperature to about 85-90 C. and the resin solution is concentrated toabout 60-70% solids by vacuum distillation. The resulting resin soiutionmaybe diluted to about 50% solids with any desired solvent or water trap. During the distillation about 550 During the diswill be about loo-105 C. The pressure is lowered sufliciently to reduce the vapor temperature toabout 85-90 C. and the resin solution is concentrated to about -70% solids lay-vacuum distillation. The resulting resin solution may be diluted to about' 50% solids with any desired solvent or diluent, e. g., xylene.

Preparation of melamine-formaldehyde Resin "3 Parts This mixture is placed in a reflux apparatus which I is provided 'with a condenser and a suitable water trap through which the reflux condensate passes onits return to the reaction chamber and. in

which the essentially aqueous fraction of the condensatemay be separated from the essentially non-aqueous fraction and means is provided so that the former fraction maybe drawn off if desirable. The reaction mixture is refluxed at a temperature of about 91-93? C. at atmospheric pressure for 6-12 hours. The water is removed by azeotropic distillation from the reactionmixture during the reflux operation beginning preferably after about 2-5 hours have elapsed and the water so removed is separated from the reflux. Y

condensate in the Formalin (6 mols) (37% formaldehyde in water) 486.6 n-Butanol 440 This mixture is placed in a reflux apparatus which is provided with a condenser and a suitabl water trap through which the reflux condensate passes on its return to the reaction chamber and in which the essentially aqueous fraction of the condensate may be separated from the essentially nonaqueous fraction and means is provided so that the former fraction may be drawn 011 if desirable. The reaction mixture is refluxed at a temperature of about 91-93 C. at atmospheric pressure for 6-12 hours. The water is removed by azeotropic distillation from the reaction mixture during the reflux operation beginning preferably after about 2-5 hours have elapsed and the water so removed is separated from the reflux condensate in the additional parts of butanol are added gradually. When the reflux condensate is substantially anhydrous the vapor temperature will be about 100-105 C. The pressure is lowered sufiiciently to reduce the vapor temperature to about -90 C. and the resin solution is concentrated to about 60-70% solids by vacuum distillation. The resulting. resin solution may be diluted to about 50% solids with any desired solvent or diluent. e. g., xylene.

7. Preparation of melamine-formaldehyde Resin D Parts Melamine-formaldehyde (molal ratio 1:4')

spray-dried powder 300 n-Propannl 1200 Methyl acid phosphate 3 centrated at about 50-60 C. until 767 parts of Preparation of melamine-formaldehyde Resin E Parts Melamine (1 mol) 126 Formalin (5 mols) (37% formaldehyde in water) 405.5 n-Henl alcohol -1 500 Methyl alcohol 200 This mixture .is placed in a reflux apparatus which is provided with a condenser and a suitable water-trap through which the reflux conwater 'trap. During'the dis- 75, densate passes on its return tothe reaction chamof the condensate may be separated from the essentially non-aqueous fraction and means is provided so that the former fraction may be drawn off if desirable. The reaction mixture is refluxed at a temperature of about 80-85 C. at atmospheric pressure for 6-12 hours. The water is removed by azeotropic distillation from the reaction mixture during the reflux operation beginning preferably after about2-5 hours have elapsed and the water so removed is separated from the reflux condensate in the water trap. When the reflux condensate is substantially anhydrous the vapor temperature will be about 100-105 C. The pressure is lowered sufliciently to reduce the vapor temperature to about 85-90 C. and the resin solution is concentrated to about 60-70% solids by vacuum distillation. This solution is essentially a hexylated resin in hexyl alcohol, all

-or nearly all of the methanol having been eliminated from it during the distillation. The resulting resin solution may be diluted to about 50%- solids with any desired solvent or diluent, e. g.

xylene. Preparation of melamine-formaldehyde Resin "F Parts Melamine-formaldehyde (molal ratio 1:4)

spray-dried powder 200 2-ethyl hexanol 280 n-Butanol 320 Methyl acid phosphate; 4

The melamine-formaldehyde condensation product is obtained by refluxing melamine and formalin 37% formaldehyde in water) in the molal ratio of 1:4 at a pH of about 7-9 for about 3 hoursand then spray-drying.

The spray-dried melamine-formaldehyde powder; octanol, butanol and methyl acid phosphate are heated to about 100-10550. in 30 minutes and refluxed about 30 minutes. This solution is vacuum concentrated at about 50-70 C. to form a f product containing about 50% solids.

Alkylated melamine-formaldehyde resins may be produced in accordance with the procedures outlined above, as well as in any other suitable manner. Aqueous syrups "of melamine-formaldehyde resins may be first produced and then 1 alkylated either simultaneously with'dehydration or subsequent 'to dehydration. Generally the simultaneous condensation of melamine, formaldehyde and a suitable alcohol is used because of convenience. In order to facilitate the alkylation with the higher alcohols, e. g., the amylalcohols,

hexyl alcohols and the octanols, a low boilin ated solvents such as ethylene dichloride, etc., may be added to the original solutions of polymerized rubber and melamine-formaldehyde resin in order to produce perfectly clear solutions if such solutions are not originally obtained.

While formaldehyde has been used in the previous'examples, it will be obvious that the various polymers of formaldehyde, e. g., paraformaldehyde or substances which yield formaldehyde may be used in place of part or all of the formaldehyde.

As indicated by the above examples polymerized rubber (cyclized rubber obtained by reacting the rubber with amphoteric metal halides) has been found to be compatible with melamine-formaldehyde resins wherein the molal ratio of formaldehyde to melamine is at or above about 4:1. While higher ratios of formaldehyde to melamine than 6: 1 may be used, it is generally undesirable inasmuch as formaldehyde is lost during the curing so that usually the product in its cured condition does not contain more than about 6 mols 'of formaldehyde to 1 mol of melamine.

The resins may be alkylated with any of the straight chain or branched chain acyclic alcohols,

' containing from 3 to 8 carbon atoms. The term alkylated melamine-formaldehyde resin is intended to denote compositions which are reacted with an alcohol. p

Our products may be plasticized with awide variety of materials such as the alkyl phthalates, tricresyl phosphate, various alkyd resins, particularly the fatty oil acid modified alkyd resins,

' etc.

Various fillers, pigments, dyes and lakes may be added to our compositions, e. g., lithopone, zinc oxide, titanium oxide, ferric oxide, Prussian blue, toluidine red, malachite green, mica, glass fibers, ground glass, powdered silica, etc.

Curing catalysts may be incorporated in the compositions to effect a-more rapid curing of the melamine-formaldehyde resins or to. enable the resin to be cured at lower temperatures than indicated in the above examples. Such substances are for instance phosphoric acid, ammonium salts of phosphoric acid, etc.

Other resinous compositions may be included in various coating compositions. e. 2., urea-formaldehyde resins, phenol-formaldehyde resins, ethyl cellulose, cellulose acetate, nitrocellulose, etc.

Polymerized rubber (cyclized rubber obtained by reacting the rubber with amphoteric metal halides) suitable for use in accordance with this invention is prepared by heating crepe rubber in the presence of stannic chloride, ferric chloride, boron fluoride, chlorostannic acid, etc. The production of materials of this type is described in United States Patents Nos. 1,751,817, 1,797,188

' and 1,846,247, wherein the use of various metal her as used in the specification and claims is intended to cover only products prepared in accordance with the foregoing description. The

material used in the above examples which is known as Pliolite and sold by the Goodyear Tire and Rubber Company, is a thermoplastic amber condensation may-be carried-out either with or without an acldcatalyst and in some instances basic. catalysts may desirably be utilized.

The melamine-formaldehyde resins vary slightly according to minor variatio in control during their production and in some instances small roportions of a suitable solvent material, e. hydrocarbo'n, solvents such as toluene, the chlorlm colored material which softens at 55-65 C. and which has a specific gravity of about 1.05. This composition contains about of rubber hydrocarbons.

- Our mixtures of melamine-formaldehyde resins and polymerized rubber, otherwise known as r cyclizedrubber obtained by reacting the rubber with amphoteric metal halides. are especially suitprovide adherent coatings, as well as for creaseproofing processes. One advantage of our mixtures is that thixotropic compositions may readily be produced and this property is especially desirable in wall paints, in printinginks, etc.

Our products have good light resistance, good acid resistance, good alkaliresistance, excellent water resistance, good adhesion, excellent abrav sive resistance, and they are also resistant to the action 01 solvent materials; This latter property,

together with th reduced thermoplasticity as her with amphoteric metal halides melamine-formaldehyde resin which has been alkylated with an acyclic alcohol containing 3 to 8 carbon atoms, wherein the molal ratio of formaldehyde to melamine is between about 4:1 and about 6:1 and wherein the weight ratio of the cyclized rubber obtained by reacting the rubto melamine resin is at least about 3:2. I 2. A coating composition containing substantial amounts of cyclized rubber obtained by reacting the rubber with amphoteric metal halides and a melamine-formaldehyde resin which has been alkylated with n-butylalcohol, wherein the molal ratio of formaldehyde to melamine is between about 4:1 and about 6:1 and wherein the weight ratio of the cyclized rubber obtained by reacting the rubber with amphoteric metal halides to compared to ordinary polymerized rubber, otherwise known as cyciized rubber obtained by reacting the rubber with amphoteric metal halides,

compositions, is primarily broughtabout by the melamine-formaldehyde resins.

Protective coatings made according to this invention are especially useful in industrial plants where materials are used, not only in painting walls and equipment, but also in coating con-" tainers .which are used for dilute'acids, alkaline solutions, water, salt water; etc.

The term compatible as used herein i intended to denote compositions, films-oi which are clear and homogeneous after baking. 7

Obviously many modifications and variations in the processes and compositions described above may be made without departing from the spirit and scope of the invention as defind in the appended claims.

. We claim:

1. A coating composition containing substantial amounts of cyclized rubber obtained by reacting the rubber with amphoteric metal halides and a amounts of cyclized rubber obtained by reacting the rubber with amphoteric metal halides and a.

melamine-formaldehyde resinwhich has been alkylated with n-hexyl alcohol, wherein the molal ratio of formaldehyde to melamine is between about 4,: 1 andabout- 6:1 and wherein the weight ratio of the cyclized rubber obtained by reacting the rubber with amphoteric metal halides to melamine resin is at least about 3:2.

4. A coating. composition containing substantial amounts of cyclized rubber obtained by reacting the rubber with amphoteric metal halides and a melamine-formaldehyde resin which has been alkylated with 2-ethyl hexanol, wherein the molal 7, ratio of formaldehydeto melamine isbetween 

